adding quickfix library

quickfix/parser.go

@@ -0,0 +1,165 @@
+// Copyright (c) quickfixengine.org  All rights reserved.
+//
+// This file may be distributed under the terms of the quickfixengine.org
+// license as defined by quickfixengine.org and appearing in the file
+// LICENSE included in the packaging of this file.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING
+// THE WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A
+// PARTICULAR PURPOSE.
+//
+// See http://www.quickfixengine.org/LICENSE for licensing information.
+//
+// Contact ask@quickfixengine.org if any conditions of this licensing
+// are not clear to you.
+
+package quickfix
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"time"
+)
+
+const (
+	defaultBufSize = 4096
+)
+
+type parser struct {
+	// Buffer is a slice of bigBuffer.
+	bigBuffer, buffer []byte
+	reader            io.Reader
+	lastRead          time.Time
+}
+
+func newParser(reader io.Reader) *parser {
+	return &parser{reader: reader}
+}
+
+func (p *parser) readMore() (int, error) {
+	if len(p.buffer) == cap(p.buffer) {
+		var newBuffer []byte
+		switch {
+		// Initialize the parser.
+		case len(p.bigBuffer) == 0:
+			p.bigBuffer = make([]byte, defaultBufSize)
+			newBuffer = p.bigBuffer[0:0]
+
+		// Shift buffer back to the start of bigBuffer.
+		case 2*len(p.buffer) <= len(p.bigBuffer):
+			newBuffer = p.bigBuffer[0:len(p.buffer)]
+
+		// Reallocate big buffer with enough space to shift buffer.
+		default:
+			p.bigBuffer = make([]byte, 2*len(p.buffer))
+			newBuffer = p.bigBuffer[0:len(p.buffer)]
+		}
+
+		copy(newBuffer, p.buffer)
+		p.buffer = newBuffer
+	}
+
+	n, e := p.reader.Read(p.buffer[len(p.buffer):cap(p.buffer)])
+	p.lastRead = time.Now()
+	p.buffer = p.buffer[:len(p.buffer)+n]
+	return n, e
+}
+
+func (p *parser) findIndex(delim []byte) (int, error) {
+	return p.findIndexAfterOffset(0, delim)
+}
+
+func (p *parser) findIndexAfterOffset(offset int, delim []byte) (int, error) {
+	for {
+		if offset > len(p.buffer) {
+			if n, err := p.readMore(); n == 0 && err != nil {
+				return -1, err
+			}
+
+			continue
+		}
+
+		if index := bytes.Index(p.buffer[offset:], delim); index != -1 {
+			return index + offset, nil
+		}
+
+		n, err := p.readMore()
+
+		if n == 0 && err != nil {
+			return -1, err
+		}
+	}
+}
+
+func (p *parser) findStart() (int, error) {
+	return p.findIndex([]byte("8="))
+}
+
+func (p *parser) findEndAfterOffset(offset int) (int, error) {
+	index, err := p.findIndexAfterOffset(offset, []byte("\00110="))
+	if err != nil {
+		return index, err
+	}
+
+	index, err = p.findIndexAfterOffset(index+1, []byte("\001"))
+	if err != nil {
+		return index, err
+	}
+
+	return index + 1, nil
+}
+
+func (p *parser) jumpLength() (int, error) {
+	lengthIndex, err := p.findIndex([]byte("
9="))
+	if err != nil {
+		return 0, err
+	}
+
+	lengthIndex += 3
+
+	offset, err := p.findIndexAfterOffset(lengthIndex, []byte("\001"))
+	if err != nil {
+		return 0, err
+	}
+
+	if offset == lengthIndex {
+		return 0, errors.New("No length given")
+	}
+
+	length, err := atoi(p.buffer[lengthIndex:offset])
+	if err != nil {
+		return length, err
+	}
+
+	if length <= 0 {
+		return length, errors.New("Invalid length")
+	}
+
+	return offset + length, nil
+}
+
+func (p *parser) ReadMessage() (msgBytes *bytes.Buffer, err error) {
+	start, err := p.findStart()
+	if err != nil {
+		return
+	}
+	p.buffer = p.buffer[start:]
+
+	index, err := p.jumpLength()
+	if err != nil {
+		return
+	}
+
+	index, err = p.findEndAfterOffset(index)
+	if err != nil {
+		return
+	}
+
+	msgBytes = new(bytes.Buffer)
+	msgBytes.Reset()
+	msgBytes.Write(p.buffer[:index])
+	p.buffer = p.buffer[index:]
+
+	return
+}